Switch to CDMA if Ethernet is down and switch back to Ethernet once it is up. Tolerance time = 1minutes

switcher.sh

#!/bin/bash
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
dir=/home/odroid/Switcher/

#Check for interface
INTERFACE=`head -n1 $dir/switcher.log  | awk '{print $3}'`
eth_iface=`ls /sys/class/net | grep eth`
CDMA_NUM=`sed '2q;d' $dir/switcher.log | awk '{print $3}'`
hit=`cat $dir/hit`
new_hit=$(($hit+1))

#First ping hydrology.gov.np and check if internet is working or not
function pinger()
{
	if [ "`ping -c 5 hydrology.gov.np`" ]
	then
		INTERNET=1 #YES INTERNET
	else
		INTERNET=0 #NO INTERNET
	fi
}

function cdma()
{
	ifconfig $eth_iface down
	pon.wvdial
	sleep 15
	if [ $? -eq 0 ]
	then
		pinger
		if [ "$INTERNET" == "1" ]
		then
			sed -i "1s/$INTERFACE/CDMA/" $dir/switcher.log
			sed -i "2s/$CDMA_NUM/$(($CDMA_NUM+1))/" $dir/switcher.log
			exit
		fi
	fi
	ifconfig $eth_iface down
}
			


function ethernet()
{
	sleep 5
	ifconfig $eth_iface down
	ifconfig $eth_iface up 
	timeout 5 dhclient $eth_iface
	if [ $? -eq 0 ]
	then
		pinger
		if [ "$INTERNET" == "1" ]
		then 
			sed -i "1s/$INTERFACE/ETHERNET/" $dir/switcher.log
			sed -i "2s/$CDMA_NUM/0/" $dir/switcher.log
			if [ "`ifconfig | grep ppp0`" ]
			then
				poff.wvdial
				dhclient eth0
			fi
			
		else
			cdma
		fi
	else
		ifconfig $eth_iface down
		if [ "$INTERFACE" == "CDMA" ]
		then
			exit
		else
			cdma
		fi
	fi
	dhclient $eth_iface
}
pinger

if [ "$INTERFACE" == "ETHERNET" ] && [ "$INTERNET" == "1" ]
then
	if [ "`ifconfig | grep ppp0`" ]
	then
		poff.wvdial
		ifconfig ppp0 down
		dhclient eth0
	fi
	exit
elif [ "$INTERFACE" == "ETHERNET" ] && [ "$INTERNET" == "0" ]
then
	#first try to get ethernet working
	ethernet
elif [ "$INTERFACE" == "CDMA" ] && [ "$INTERNET" == "1" ]
then
	ethernet
elif [ "$INTERFACE" == "CDMA" ] && [ "$INTERNET" == "0" ]
then
	ethernet
else
	continue
fi